<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <h2>JS原生绑定事件</h2>
    <button class="btn" onclick="aa()">绑定事件</button>
</body>
<script>
    function aa() {
        for (let i = 0; i < 5; i++) {
            console.log(i)
        }
    }
</script>

</html>